Electronic devices such as servers are installed in a data center. As a method of cooling the electronic devices, there is a method using outside air. According to this method, the outside air is taken into the data center by rotating fans, and the electronic devices are cooled directly with the outside air, without the outside air being cooled by using a heat exchanger and the like. Thus, this method does not require electric power for the heat exchanger and the like, and is therefore able to contribute to energy saving in the whole of the data center.
However, when the outside air is directly used in the case where the outside air temperature is low as in winter, the electronic devices may be cooled excessively and the temperatures of the electronic devices may deviate from their operation guarantee ranges. For this reason, it is desirable to warm the inside of the data center by using some mechanisms. However, in some operating conditions of the mechanisms, there is a risk of an increase in power consumption in the data center.
Note that techniques relating to the present application are disclosed in Japanese Laid-open Patent Publication No. 02-290454 and Japanese Laid-open Patent Publication No. 08-193727.